The Politics of Aristotle

by Aristotle

  6 · In aromatic trees it is sometimes the root which is aromatic, sometimes the bark, sometimes the flower, and sometimes the wood; in other cases every part is aromatic, in the balsam for example.

  Some trees come into existence by being planted, some from seeds, others [30] spontaneously. Those which are planted are separated either from the root, the stem, the branches, or the seed, or else the whole is transplanted; some are slightly bruised before being planted. Some are planted in the earth again, others are planted, that is, grafted, on other trees. It is better to graft on trees which are [35] similar and have the same proportions; the best results are obtained in the grafting, for instance, of apple on pear, fig on fig, or vine on vine. Sometimes grafting of different species is resorted to, bay, for example, on wild plane, olive-trees on terebinth, mulberries on a number of different trees, and wild trees on garden trees. [821a1] Every plant does not produce a seed similar to that from which it is sprung; some produce a better seed, others a worse, and good trees sometimes grow from bad [5] seeds, as in the case of bitter almonds and pomegranates. In some trees too, when they are weak, the seed fails, in the pine for example, and the palm. But a good plant is not likely to be produced from a bad seed, nor a bad tree from a good seed. This [10] often occurs, however, among animals.

  A tree which has hard bark and has become barren, if its root be split and a stone inserted in the cleft will become fruitful again. In palms too, if the leaves or pollen or bark of the male palm be applied to the leaves of the female palm so as to [15] cohere,10 its fruits will come to maturity quickly, and it will prevent their falling off. The male can be distinguished from the female palm, because it sprouts first and its leaves are small, and also because of its odour; sometimes all these conditions are present, sometimes only some of them. It will perhaps happen that the wind will [20] bear the odour of the male to the female palm, and then the dates will come to maturity; the foliage of the male will also cohere to that of the female palm when they catch in one another. Wild fig-trees, too, spread along the ground and contribute to garden fig-trees; similarly wild olives contribute to olives, when they [25] are planted together.

  7 · Again, some plants change into other species, the nut-tree, for example, when it becomes old. It is also said that catmint changes into mint, and basil, if [30] plucked up and planted by the Persian Gulf, will perhaps turn into thyme. Also wheat and flax change into tares. The poisonous nightshade which grows in Persia changes its nature if transplanted into Egypt and Jerusalem and becomes edible. [35] Almond-trees and pomegranates change their condition for the better under cultivation. Pomegranates are improved by being manured with pigs’ dung and watered with fresh cold water. Almond-trees with pegs driven into them exude gum for a long while. Many wild plants are thus artificially changed into garden plants. [821b1] Position and care, and, above all, the season of planting, contribute to this process. Some plants require some one to plant them, others do not. Most plants are planted in the spring, a few in the winter and autumn, very few in the summer after the [5] rising of the dogstar; planting at this season takes place in few places—nowhere except in the Crimea. In Egypt planting only takes place once in the year.

  Some trees produce leaves from their roots, some from their buds, some from [10] the wood, others from every part. In some they are near the ground, in others far from it, in others they are neither high nor low; others produce a few leaves at various times. Some trees bear fruit once a year, others several times, and their fruit does not mature, but remains unripe. Certain trees are very fruitful over a long [15] period, as, for instance, fig-trees. Some bear fruit one year and then recuperate for a year, as do olive-trees, although they produce a number of boughs which cover them. Some trees are more productive when they are young than when they are old; others, on the contrary, are more fertile when they are old, almond-trees, for [20] example, and pear-trees and holm-oaks. Wild and garden plants can be distinguished by virtue of the male and female, each being recognizable by its peculiar characteristics; for the male is thicker and harder and has more branches and less [25] moisture and a smaller fruit, and does not reach such maturity; the leaves, too, and likewise the suckers are different.

  In considering this we should form some conjectures whereby we may know trees and their seeds apart, and similarly in the case of small herbs. We must [30] consider what the ancients have said on these points, and examine the works written upon them. We shall only be able to take a brief survey and extract the essence of them. This means that we shall consider those plants which contain oil, those which [35] produce seeds, and those which produce wine, and plants which have medicinal properties, and those which destroy life. All these particulars about trees and plants are well known. But in order to know their causes, we ought to inquire into their production, and discover why certain plants grow in certain places and not in others, and at certain seasons and not at others; we must examine their methods of planting, their roots, their differences of sap and odour and juice and gum, and the [822a1] excellence and defects of particular plants, and the fact that the fruits of some trees last but not those of others, and why some fruits putrefy quickly, others more slowly. We must inquire into the properties of all plants, and particularly those of [5] their roots; and why some fruits grow soft while others do not; and why some arouse lust, others cause sleep, and others are fatal to life; and many other differences; and why the fruits of some produce milk, of others not.

  BOOK II

  [10] 1 · A plant has three powers, the first derived from the element of earth, the second from that of water, the third from that of fire. From the earth the plant [15] derives its fixity, from water its solidity, and from fire the unity of its fixity. We see much the same thing in vessels of pottery, which contain three elements—clay, which is, as it were, the material of pottery; secondly, water, which binds the pottery [20] together; and, thirdly, fire, which draws its parts together, until it completes the process of manufacture. The appearance, then, of complete unity is due to the fire; because rarity is present in pottery according to the composition of its parts, and, when the fire heats them, the moist matter is completed, and the parts of the clay [25] will cohere together. Dryness will thus take the place of moisture, owing to the predominance of the fire and the process of concoction which takes place in all animals, plants, and metals. For concoction takes place where moisture and heat are present, when the struggle between them is allowed to run its course; and this is [30] what will take place in the concoction of stone and metals. It is not so in animals and plants; for their parts are not closely compacted, and so there is an escape of moisture from them. But in metals there is no such escape of moisture or sweating, because their parts have no rarity, and therefore they can give up nothing except parts of themselves to correspond to certain residues which are given off by animals and plants. This escape of moisture can only take place where rarity is present; and so where there is no rarity, nothing at all can be given off. Therefore that which [35] cannot be increased is solid, because that which can increase requires space in which to dilate and grow; and therefore stones, salt, and earth are always the same, neither increasing nor growing. There is motion in plants in a secondary sense, and [822b1] this is a form of attraction, namely, the force of the earthly element which attracts moisture; in this attraction there will be motion, and the moisture makes for a certain position, and the process of concoction is thus in a certain way completed. And so small plants usually come into being in the short space of a single day, unlike [5] animals; for the nature of animals is in itself different; for no concoction will take place except by the use of material in the animal itself. But the material of which the plant is formed is near at hand, and therefore its generation is quick, and it [10] grows and increases, because it is rare, more quickly than if it were dense. For that which is dense requires many powers on account of the diversity of its form and the extension of its parts in relation to one another. Consequently the generation of a plant is
quicker on account of the similarity of its parts to one another, and the [15] completion of its growth is speedier. Now the parts of plants are usually rare, because the heat draws the moisture into the extremities of the plant, and the material is distributed through all its parts, and that which is superfluous will flow away; just as in a bath the heat attracts the moisture and turns it into vapour which [20] rises, and, when it is present in superfluity, it will turn into drops of water. Similarly in animals and plants, the superfluities ascend from the lower into the upper parts and then descend in their action from the upper to the lower parts.

  We find the same phenomenon in streams which are generated underground [25] and come forth from mountains, and whose material is rain. When the waters increase and are confined within the earth, an excess of vapour will be produced from them on account of their compression underground, and the vapour will break its way through the earth and fountains and streams will appear, which were [30] formerly hidden.

  2 · We have set forth the causes which produce springs and rivers in the book on Meteorology. An earthquake frequently discloses springs and rivers which had [35] not before been visible, when the earth is rent by vapour. We also often find that springs and rivers are submerged when an earthquake takes place. But this does not happen in the case of plants, because air is present in the rarity of their parts. This is [823a1] indicated by the fact that an earthquake never takes place in sandy localities, but only where the ground is hard, that is in districts of water and mountains. Earthquakes occur similarly in these districts, because water and stone are solid, [5] and it is the nature of warm, dry air to ascend. When, therefore, the particles of air become massed together, they gain force and thrust up the ground and the vapour [10] makes its way out; whereas, if the ground were rare, the vapour would make its way out gradually from the first. But the ground being solid, it does not make its way out [15] gradually, but its parts collect, and it is then strong enough to rend the earth. This, then, is the cause of earthquakes in solid bodies; there will, therefore, be nothing to [20] correspond to an earthquake in the parts of plants and animals, though it will occur in other things—often, for example, in pottery and glass, and in some cases in minerals. Any body which has considerable rarity tends to rise upwards, for the air supports it. This we often see when we throw a gold coin or some other heavy substance into the water and it immediately sinks; whereas if we throw in a piece of wood, which has rarity in it, it does not sink. A gold coin sinks not because of its [25] leaf-like form nor on account of its weight, but because it is solid. That which has rarity can never altogether sink. Ebony and similar substances sink because there is very little rarity in them, and therefore there will not be air present to support them; [30] and so they sink, because their parts are practically solid. Oil and leaves always float on the surface of water. We will now prove this. We know that heat and moisture are present in these substances; and it is characteristic of moisture to [35] cohere with particles of water, while it is characteristic of heat that it causes things to rise and makes its way towards the particles of air; and it is the habit of water to raise objects to its surface, and of air to rise upwards; and water does not rise above [40] its surface, because the whole surface of the water is one and the same, and consequently the air rises with the oil above the water. Some stones too float on [823b1] water, because rarity is present in them and is greater in quantity than the matter of which they are formed, and consequently11 the space occupied by air will be greater than that occupied by the earthly element. It is the nature of water to take up a position above the earth, and of air to rise above water; the material, therefore, which composes the stone, which is of the element of earth, sinks in the water, while [5] the element of air enclosed in the stone rises above the water. Each element therefore attracts its like in a contrary direction to the element with which it is combined. If, then, one element is equal to the other, half the stone will be submerged and half will project above the surface; but if the air is present in greater [10] quantity, the stone will float above the water. The weight of trees is made up in the same way. (These stones are due to a violent collision of waves, and are originally foam which forms an oily milk; when the wave is dashed against the sand, the sand will collect the oily foam, and the dryness of the sea will dry it up together with the [15] superfluous salt, and the particles of sand will collect, and thus in the long process of time stones will be formed.)

  The presence of sand under the sea is explained by the fact that earth always [20] has a fresh flavour, and when water stands it will be prevented from undergoing any change, and will form an enclosed mass of water in the place where it is, and the air will not draw it up; the particles of earth, therefore, gain the upper hand and [25] become salty, and gradually acquire heat. (Now soil is found in its natural state in fresh running water, because there the water is sweet and light.) And because the [30] dryness of the earth gains the upper hand in the water, it changes it into an earthy nature, or something like it, and makes both the earth and water crisp; and this process of drying goes on as long as the earth remains in its place and there is water still left, and it splits up the soil into small particles; and for this reason the earth near the sea is always sandy. The same thing happens on plains which have nothing [35] to protect them from the sun, and which are far from fresh water; the sun has dried up the particles of fresh moisture and that which is of the nature of earth has remained; and because the sun shines continually upon an exposed place of this [40] kind, the parts of the soil become separated and sand is thus formed. A further sign of this is that if we dig deep down in a desert, we shall find natural soil. Natural soil, therefore, will be the basis of sand, and will only become sand accidentally and [824a1] under certain circumstances, namely, when the sun’s rays dwell on it for a long time and it is far removed from fresh water. The saltness of the sea is to be accounted for in a similar way; for the basis of all water is fresh water, and saltness is accidental, [5] occurring only under the circumstances which we have mentioned. The fact that the earth is below the sea and the sea naturally and necessarily above the earth is a self-evident proof of this. Some, however, have held that the common element is [10] that which is present in the greatest quantity, and that there is a greater quantity of water in the sea than elsewhere, and that, therefore, sea-water is the element present in all water. But water naturally has its position above the earth and is lighter than it; for we have already shown that water is at a higher elevation than [15] the earth according to the altitude at which the mass of water stands. Let us take two vessels of the same size and place fresh water in one and salt water in the other; then let us take an egg and place it in the fresh water; it will sink, whereas, if we [20] place it in the salt water, it will float. It therefore rises above the particles of salt water because these particles do not let it sink,12 as do those of fresh water, but they can uphold the weight, which therefore does not sink. So in the Dead Sea no animal [25] can sink, nor is any animal life produced in it, because dryness predominates in it and it is like the form of earth. It is clear, therefore, that dense water finds a lower level than water which is not dense; for the dense is of the nature of earth, the rare of [30] the nature of air; therefore, fresh water stands at a higher elevation than any other water, and is therefore further removed from earth. Now we already know that the water which is furthest removed from earth is the natural water, and we have shown that fresh water is higher in position than all other kinds of water; as this sign shows, [35] then, it certainly and necessarily is the natural water. Salt water is also produced in pools, because fresh water becomes salt. The saltness, therefore, of the earth prevails over that saltiness, and the air will remain enclosed, and the mass of water will not therefore be fresh. Saltness may also be produced from water by being given [824b1] off from it like sweat.

  3 · So too in the case of plants: their species will be formed, not from a simple element, but by a process of composition, just as saltness and the substance
of sand [5] are formed from the water of the sea. For vapours which rise, when they become solidified, will be able to conceive these plants, and the air will descend and bedew [10] the ground, and from it will come forth the form of their seeds through the powerful influence of the stars. But plants must necessarily have some material, and this material is water. There are, however, different kinds of water, and water only rises [15] if it is fresh, and salt water is heavier than fresh; and so that which rises above water is rarer than water. When, therefore, the air draws it up, it will become rarefied and rise still higher; and this is why fountains and streams are formed in mountains. [20] Similarly phlegm and blood rise to the brain, and all foods also rise; so too all water rises. Even salt water rises in that part of it which heat dries out into the element of air, and, because air is always higher than water, that which rises above salt water is [25] fresh. We often find the same thing taking place in baths. When heat takes hold of salt water, its parts will be rarefied, and vapour will rise in a contrary direction to the depth of the bath, and the particles of salt and the natural moisture become [30] separated, for the latter is of the nature of air and follows the vapour; and cloud after cloud of vapour rises upwards, and when they reach the roof they press upon it. The vapour will thus collect and become condensed, and will turn into drops of fresh [35] water dripping down, and so in salt baths the vapour will always be fresh.